How fast is the iMac G5 compared to the iMac G4 Flat-Panel and Power Macintosh G5?

Please note that all systems mentioned in this Q&A have been discontinued.

According to benchmarks from the always reliable MacWorld, the original iMac G5/1.8 17-Inch and G5/1.8 20-Inch were "35 percent faster" than the iMac G4/1.25 20-Inch "Flat-Panel" (USB 2.0) that each replaced.

Photo Credit: Apple Computer (iMac G4 Flat-Panel - Left, iMac G5 - Right)

Likewise, MacWorld reported that in tests using applications "like Cinema 4D and Apple's Compressor that make the most of two processors" the Power Macintosh G5/1.8 DP (PCI) was "twice as fast" as the original iMac G5/1.8 17-Inch and G5/1.8 20-Inch. The Speedmark benchmarking software also demonstrated that the Power Mac G5/1.8 DP (PCI) "was about 19 percent faster than the original iMac G5 models in the suite's 15 tests."

MacWorld also released benchmarks for the "Ambient Light Sensor" iMac G5 models. With the Speedmark 4 benchmarking program, the entry-level iMac G5/1.8 17-Inch (ALS) scored a 163 and the iMac G5/2.0 17-Inch (ALS) and 20-Inch (ALS) each scored a 174. This is compared to the original iMac G5/1.8 20-Inch, which scored a 155, and the odd ball Power Macintosh G5/1.8 (PCI) which scored a 160.

Regarding the "Ambient Light Sensor" models, MacWorld concluded:

With the help of faster processors in all but the entry-level 1.8 GHz 17-inch iMac, it is no surprise that both 2.0 GHz models out-performed the previous top-of-the-line iMac. But with the help of the other internal improvements, the latest 17-inch, 1.8 GHz iMac also performed markedly better than [the previous] year's model.

For the final iMac G5 "iSight" models, MacWorld only compared the systems to their immediate predecessor using the Speedmark 4 benchmarking program. The iMac G5/1.9 17-Inch (iSight) scored a 178 and the iMac G5/2.1 20-Inch (iSight) scored a 190. This compared to the to the replaced iMac G5/2.0 20-Inch (ALS) which also scored a 178.